Printer output, such as text on paper, normally occurs when a computer sends a digital file to a printing device, such as a printer, copier, facsimile, or the like. This digital file often contains information associated with and necessary for the printing device to print the output. Examples of this information include the number of copies, the type of paper to be used, the orientation for printing the output, and so forth. In order for the printing device to glean this information, and, therefore, correctly print the output, a processor associated with the printing device reads the received digital file.
Sometimes, however, after the printing device receives the digital file, the printing device fails to print the output in exact accordance with the digital file's instructions. As a result, printing errors occur in the output. For example, in the black-and-white context, the printing device may print black on the output where white should be, that is, “unintended black,” and/or the printing device may not print black on the output where black should be, that is, “missing black.” Additional examples of undesirable defects on the output include spots, lines, streaks, bleeding, haloing, tenting, trail-edge deletion and starvation. Regardless of the type of defect on the output, businesses either selling printing devices or heavily relying on the accuracy of printing devices may desire to validate the output accuracy of such printing devices.
Printing verification systems (PVSs), such as that offered by IBM, exist to validate the accuracy of printing devices. In short, a PVS is a printing inspection device which can inspect the whole surface of a printed matter in detail at high speed. More specifically, a typical PVS includes an associated high speed printer that prints about 300 sheets/minute, and the output from this printer is on a continuous form sent through an associated duplex scanner, i.e., two cameras, wherein each one scans an image of the opposing sides of the output. PVS then compares the scanned images to the printed images of the output, and determines whether the scanned images are the same as the printed images of the output. If the printing device under test by PVS is working properly, then the scanned images are the same as the printed images of the output. However, if differences exist, such as “unintended black” or “missing black” is found by the PVS analyzer module of PVS, then PVS will report that the printing device is producing defects in the output. Such defects will be reported on a display, such as on a graphical user interface (GUI), associated with PVS.
Despite the existence of PVS's to test for defects in a printing device's output, problems remain in determining whether printing devices are indeed working properly. If a PVS is malfunctioning, and, thereby, fails to report defects for a printing device when defects indeed exist, then the PVS is not serving its intended function. Reliance, therefore, by the industry on a malfunctioning PVS is entirely possible, which can lead to catastrophic and unpredictable consequences for businesses that heavily rely on the accuracy of its printing devices that they believe, albeit wrongly, are working properly. Unfortunately, no known measures, much less rapid, automated measures, exist for determining whether a PVS is analyzing a printing device's output properly.
A need, therefore, exists for automated methods, systems, and media for testing the accuracy of a PVS.